The best way to keep bookmarks in sync between different FireFox installations is Mozilla Sync. Give it a try! It's great and doesn't reveal your data to a third party (even Mozilla).

Check https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer for a description how to export it to a HTML and/or or a importable file.
The best way to keep bookmarks in sync between different FireFox installations is Mozilla Sync. Give it a try! It's great and doesn't reveal your data to a third party (even Mozilla).